1. Field of the Invention
This invention relates to a right angle drive attachment for vertical milling machines so as to permit those milling machines to utilize other tools in their operation.
2. Prior Art
Vertical milling machines, often sold under the trade name xe2x80x9cBridgeportxe2x80x9d have been utilized in machine shops for decades. Those vertical milling machines typically comprise a vertically disposed housing having and upper end and a lower end. The housing includes a frame through which an elongated hollow spindle is rotatably disposed. The spindle has a pulley on its upper end which is driven by a belt which is attached to a further pulley on an electric Motor adjacent the upper end of the housing. A quill is arranged on the lower end of the spindle. The quill is vertically displacable within the housing. A draw bar is arranged within the hollow spindle and has a lower end which is threaded into the top of a collet such as an xe2x80x9cR-8xe2x80x9d collet. The collet comprises an output shaft for the vertical milling machine. A tool is typically placed within the lower end of the collet for machining a metal piece thereunder.
The upper end of the draw bar may extend through the upper end of the housing for the vertical milling machine. Some milling machines may have been enhanced by the use of a power draw bar arrangement disposed on top of the housing of the milling machine. This power draw bar arrangement may be utilized to displace vertically the draw bar within the housing and quill to effect a rapid change of the collet and the tool held thereby.
However, if the machinist wanted to use a right angle drive with that particular vertical milling machine, the power drive arrangement would have to be removed from the top or head of the vertical milling machine and a longer manual draw bar would have to be inserted through the spindle and into engagement with a special elongated collet mated with a bevel gear in the right angle head. The draw bar would have a lower end with threads thereon screw into the upper end of the elongated collet comprising the input shaft of the right angle drive head. This changing of components in the milling machine for changing the operation of the milling machine is very time consuming and cuts into the productivity of the machinist and cuts down on the efficiency of the machine shop in which the machine is operating.
It is an object of the present invention to provide a right angle drive arrangement for a vertical milling machine which overcomes the problems of the prior art.
It is a further object of the present invention to provide a right angle drive arrangement in which there is no need to remove the power draw bar arrangement from the head of a milling machine equipped with such arrangement.
It is yet a further object of the present invention to provide a right angle drive arrangement without the need for purchasing a longer draw bar that will go into the right angle head.
It is still yet a further object of the present invention to provide an improved torque coupling arrangement over the prior art standard key and the key way arrangement in the output shaft of the vertical milling machine.
The present invention relates to a right angle drive arrangement for use with a vertical milling machine commonly known in the art as a xe2x80x9cBridgeportxe2x80x9d machine. The vertical milling machine comprises a generally vertically aligned housing having an upper or head end and a lower or drive end. A draw bar is arranged through the housing and is disposed through a spindle which rotates within the housing. The spindle, which is hollow, is disposed within a quill housing near the lower end of the machine. The spindle housing is vertically displaceable within the housing by movement of a quill handle which is engaged through a rack and pinion arrangement configured with the quill housing. The upper end of the spindle is driven by a pulley and belt arrangement with an electric motor disposed at a corresponding pulley at the proper end of the machine. The draw bar has a lower or threaded end arranged at the lower end of the spindle. Typically a collet is threadably arranged at the lower end/of the draw bar. The collet holds a cutting tool at its lower end thereof so as to act upon metal to be machined at the lower end of the quill housing. In the prior art right angle drive arrangements, the collet would be elongated and have a lowermost end which mates with a first bevel gear therewith through a longitudinally aligned key and key way arrangement. A first bevel gear is in rotatable mating engagement with a second bevel gear within the right angle drive arrangement housing. The second bevel gear has an output shaft onto which a cutting tool is disposed. Not only does a longer draw bar have to be utilized within the prior art machine, any quick change apparatus on the head of that machine needs to be removed prior to utilizing the prior art right angle drive arrangement.
In a preferred embodiment of the present invention, the regular draw bar may be left in place. The input shaft in the right angle head which mates with the internal tapered bore of the spindle of the prior art need not be utilized. In the present invention, a collar, such as for example a split ring collar or the like may be secured to the outer surface of the lower end of the spindle nose within the quill at the lower end of the vertical milling machine. The collar attached to the spindle nose preferably has for example, a slot or keyway disposed transversely thereacross. The first bevel gear in the preferred embodiment of the present invention has a key upon its hub which mates with the keyway on the drive collar on the lower end of the spindle nose. The first bevel gear rotatably engages the second bevel gear functioning as the output shaft of the right angle drive arrangement of the preferred embodiment of the present invention.
Thus, a draw bar doesn""t have to be used or screwed in by hand to a collet to use the present invention. There is no need to purchase a longer draw bar that a machinist would otherwise need with a standard prior art right angle drive head or use with a power assist mechanism. Better torque is thus provided through the present invention using the enlarged key coupling arrangement than the typically longitudinally arranged key in the standard keyway of a typical right angle drive head input shaft utilized in the prior art.
Thus there has been shown a unique right angle drive arrangement for a vertical milling machine, in which the R-8 collet output adapter is replaced with a keyway coupling which is secured by a collar onto the outer distal portion of the spindle nose. The key to xe2x80x9couter couplingxe2x80x9d fitting within the right angle head provides a solid and secure drive arrangement for the output shaft from the right angle drive arrangement.
The invention thus comprises a right angle drive arrangement for attachment to a vertical milling machine to permit the vertical milling machine to be utilized with a tool disposed on a horizontal output axis. The right angle drive comprises a right angle housing, a coupling for attachment to the outer distal portion of the vertically disposed rotatable spindle on the lower end of the vertical milling machine, a first bevel gear thus in vertical rotational alignment with its connected spindle and supported in the right angle housing, a second bevel gear in horizontal alignment with respect to the right angle housing, and an output shaft attached to the second bevel gear for supporting a tool thereon for use with a tool to horizontally work a material by the vertical milling machine. The coupling may comprise for example, a split collar to engage a lower outer peripheral portion of the spindle nose. The first bevel gear may include a drive shaft with a distal end having a key member disposed across an upper end thereof. The coupling may have a keyway arranged transversely thereacross to engagingly mate with the key arranged with the bevel gear.
The invention may also include a method of utilizing a vertical milling machine having a vertically disposed spindle with a collet therein on a lower end of the machine, the machine being arranged as a horizontally arranged tool, comprising: removing the collet from the spindle; attaching a coupling to an outer peripheral portion about the lower end of the spindle nose; attaching a right angle drive housing to the lower end of the milling machine, the housing having an arrangement of a first and a second drivable bevel gear therein; attaching a tool onto a shaft of the second bevel gear; and rotatively empowering the spindle to rotate the coupling and the bevel gears to rotate the tool for working a material thereadjacent. The coupling may comprise a collar attachable to the outer periphery of the spindle. The collar may have a keyway disposed across a lower transverse side thereof adjacent the right angle drive. The first bevel gear may have a key disposed across a drive shaft of the first bevel gear, for engagement with the keyway of the collar.